This invention relates to hand tools, and in particular the invention is concerned with a compact hand tool for projecting plumb and level reference beams of visible light for precise alignment.
A system for generating reference beams based on first generating a plumb beam of light is the invention described herein. Many self-leveling plumb laser beam generators have used ball bearings, wires, and springs. There are also many instruments which have used electronic sensors and motors to level the projector as required. A low cost automatic self-leveling laser instrument is described in U.S. Pat. Nos. 5,459,932, 5,524,352, 5,541,727, and 5,619,802 assigned to the same assignee as the present invention. The instruments of those patents are similar in application to the present invention. The disclosure of those patents is incorporated herein by reference.
In Swierski, U.S. Pat. No. 5,184,406, the instrument of which is shown in FIG. 1, a battery operated laser projector 1 is mounted in a float 2 which floats in a partially closed pan 8 of water 6. Although this does produce a plumb beam of light, there are many disadvantages to this system. The lack of liquid containment makes it difficult to transport and set up. The accuracy can be adversely affected by mishandling of the float or the battery insertion.